Inline piston pump

ABSTRACT

The present invention relates to an inline piston pump, comprising
         a driveshaft for driving the inline piston pump;   at least two pistons which are operatively connected to the driveshaft and are disposed along a driveshaft axis and are in each case disposed so as to be movable in a reciprocating manner in a piston chamber;   a suction connector for supplying a fluid to be pumped; wherein   a suction valve is disposed in at least one, preferably in each, piston chamber in order to fluidically separate a suction duct for the inflow of fluid from the piston chamber during a compression movement of the associated piston.       

     The pump is characterized in that a suction throttle valve which is conceived for varying a volumetric flow of a fluid to be pumped between the suction chamber and the suction duct is provided between the suction connector and the suction duct which in fluidic terms is connected directly to the at least one valve.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Swiss Patent Application No. 01221/19 filed on Sep. 25, 2019. The entire contents of the above-listed application is hereby incorporated by reference for all purposes.

TECHNICAL FIELD

The present invention relates to an inline piston pump which is preferably a hydraulic displacement pump in an inline piston construction mode. Said inline piston pump comprises at least two displacement units which in the direction of the driveshaft axis are disposed behind one another.

BACKGROUND AND SUMMARY

Such pumps are required in a multiplicity of applications, for example for recirculating a coolant circuit of a vehicle, for supplying a fan motor, in the recirculation of oil in an internal combustion engine. Such pumps are however also required for use in small plant equipment, for example a mini-excavator.

DE 187 08 597 discloses a suction-throttled conveying pump and herein shows the use of a suction throttle for an inline piston pump.

WO 2010 130 495 A1 discloses an inline piston pump, the driveshaft of the latter being embodied as a crankshaft.

Moreover, inline piston pumps having a camshaft are known from the prior art.

It is the object of the present invention to provide an inline piston pump which is as cost-effective as possible and offers great flexibility in terms of the installation and moreover an ideally high output density. The inflow of fluid to the displacement units comprising the pistons is moreover to be adjustable in a simple manner by way of the present invention, so as to based thereon be able to demonstrate a device for open-loop or closed-loop controlling of an inline piston pump.

This is achieved by the inline piston pump which has all of the features of claim 1. Such a pump has an advantageously constructed design and is embodied so as to be optimized in terms of installation space. Advantageous design embodiments are set forth in the dependent claims.

The inline piston pump according to the invention comprises a driveshaft for driving the at least two pistons which are operatively connected to the driveshaft and which are in each case disposed so as to be movable in a reciprocating manner in a piston chamber, a suction connector for supplying a fluid to be pumped, and a high-pressure connector for discharging the fluid to be pumped. Each of the at least two piston chambers of the inline piston pump according to the invention furthermore comprises at least two valves which are preferably embodied as check valves. When the first of these valves, which hereunder will be referred to as the suction valve, is opened there is a fluidic connection between the suction side and the piston chamber. When the second of these valves, which hereunder will be referred to as the high-pressure check valve, is opened there is a fluidic connection between the piston chamber and the high-pressure side. Such an assembly of components, which at the same time is a functional assembly and will be described below, will hereunder be referred to as a displacement unit.

A suction valve herein is fluidically connected to a chamber which in terms of the volume thereof is variable by the piston, and said suction valve ensures that, during a stroke of the piston which leads to an enlargement of this chamber, fluid from the suction side of the inline piston pump can flow into said chamber by virtue of the negative pressure and that pressurized fluid cannot flow back to the suction side during the compression stroke of the piston.

A high-pressure check valve herein is fluidically connected to a chamber which in terms of the volume thereof is variable by the piston and said high-pressure check valve ensures that (i) the fluid compressed in a compression stroke of the piston of the same displacement unit can flow out in the direction of the high-pressure output; (ii) fluid in a piston stroke which leads to an enlargement of said chamber cannot flow from the high-pressure side of the inline piston pump into said chamber; and (iii) fluid pressurized during the compression stroke of a piston in another displacement unit does not flow into said chamber.

In one embodiment of the inline piston pump according to the invention, a fluidic connection from a suction connector extends by way of a suction duct which can be used conjointly by a plurality of displacement units. Alternatively or additionally, an inline piston pump according to the invention has a fluidic connection from a high-pressure duct to a high-pressure connector which can be used conjointly by a plurality of displacement units.

In one variant, the inline piston pump between a suction connector and the suction duct which in fluidic terms is connected directly to at least one suction valve has an installation which is conceived for varying a volumetric flow of a fluid to be pumped between the suction connector and the suction duct. The installation in such a variant is situated so as to be directly proximal to the inline piston pump and is preferably integrated in the inline piston pump.

The volumetric flow of the fluid to be pumped that is able to be supplied to at least one displacement unit can be set in a simple manner by way of the installation which is disposed between a suction connector and a suction duct and which can be embodied as a suction throttle valve. The suction throttle valve herein can be moved from a position of maximum opening, in which the fluid flows through the suction throttle with an ideally minor loss of pressure, to a position of maximum throttling. There is preferably no complete constriction of the fluidic connection in the position of maximum throttling, but rather throttling which still ensures a certain throughput of fluid in order for the self-lubrication of the inline piston pump to the ensured but does not provide any volumetric flow of fluid in order for a consumer to be operated.

In one advantageous embodiment of the invention it can be provided that the setting of the intensity of throttling can take place by way of the axial position of a correspondingly designed piston which is incorporated so as to be axially displaceable in a correspondingly designed bore of the valve housing. Additionally thereto, the valve housing has corresponding recesses by way of which the fluid emanating from the suction connector can be supplied to said piston, the latter hereunder being referred to as the valve piston, and be discharged to the suction duct.

In one particularly advantageous embodiment, the bore which exists for accommodating the valve piston in the valve housing provides the presence of a closure element which after the assembly thereof can be opened again and thereafter also be closed again at any time and which is accessible from the outside even in the case of a completely assembled inline piston pump.

Alternatively or additionally, the suction throttle valve in terms of the installed position thereof is installed in such a manner that the longitudinal axis of the valve piston runs so as to be ideally parallel to the driveshaft axis.

The suction throttle valve is thus embedded in a connection between a suction connector and a suction duct in such a manner that the cross section of the connection between the suction connector and the suction duct is variable. The maximum connection cross section is available in a fully opened position such that the inline piston pump in terms of the present rotating speed of the driveshaft of said inline piston pump can suction the maximum quantity of fluid to be pumped to the at least one displacement unit which by way of this suction throttle is connected to the suction input. However, when the suction throttle valve is increasingly displaced in the direction toward the blocking position, the connection cross section is reduced such that on account thereof a shrinking quantity of fluid to be pumped can be suctioned by this at least one displacement unit.

According to an optional modification of the invention it is provided that the displaceable valve piston has a flow region which, for varying a degree of opening of a connection between the suction connector and the suction duct, in the longitudinal direction of the piston is configured by a portion which is reduced in terms of the diameter thereof, wherein the flow region can preferably be designed as an annular space.

According to the invention it can furthermore be provided that the piston is a differential piston, thus possesses at least two longitudinal portions which differ in terms of the diameters thereof, wherein the flow region is disposed in one of said regions, wherein the at least two longitudinal portions which differ in terms of the diameters thereof are preferably made initially as two separate blanks during the production.

According to the invention it can furthermore be provided that at least two forces which are aligned so as to be diametrically opposed can act on the valve piston in the axial direction of the latter. To the extent that these are only two forces, the one of the two forces facilitates a movement, or a standstill, respectively, of the valve piston in a position of wide opening, whereas the other force facilitates a movement, or a standstill, respectively, of the valve piston in a position of minor opening.

One of the two forces can in particular be caused by a compression spring on which the valve piston is supported. This herein is preferably the free end side of the longitudinal portion having the larger diameter. A sum of forces on account of the use of a plurality of springs is also possible herein, said plurality of springs exerting on the valve piston individual forces which act in the same direction. It is not necessary for all springs herein to be compression springs.

According to the invention it can moreover be provided that the valve housing has a corresponding bore by way of which there is a fluidic connection to a control surface which is present on the valve piston, on account of which a control pressure can be applied to the piston valve. Such a control surface is preferably situated on the exposed end side of the longitudinal portion having the small diameter. Alternatively or additionally, the control pressure is a pressure level which is fixedly correlated with the, or with a, respectively, high pressure level at the high-pressure connector, or at the high-pressure duct, respectively, of the inline piston pump. The control pressure can however likewise be a pressure level which can be otherwise predefined and which is derived from an external influence from such said high pressure level, that is to say a high pressure level reduced by said external influence. Furthermore, the control pressure supplied to the inline piston pump according to the invention can be generated or provided by another pressure source and therefore be at least causatively independent from a high pressure level of the inline piston pump.

In one advantageous embodiment of the invention the valve piston has at least one control surface which is aligned in such a manner that the control pressure supplied their causes of force which is directed counter to the restoring force of the at least one spring on which the valve piston is supported.

In one advantageous embodiment of the inline piston pump according to the invention it can be provided that the longitudinal portion of the valve piston that is provided with the flow region for discharging in particular such leakage fluid which flows in from a control pressure bore has a leakage duct which runs in the displacement direction of the piston, and likewise leakage fluid from the remaining internal volume of the piston bore which is situated on the side that faces the closure element. Such a leakage duct can more over also serve for damping the displacement movement of the valve piston.

The suction throttle valve preferably has at least one terminal detent position and particularly preferably two terminal detent positions of the valve piston in order for the maximum and/or the minimum throttling to be defined in a reproducible manner. In one advantageous embodiment, an end of a spring that faces away from the valve piston can interact with a closure element of a piston bore, said closure element simultaneously serving as a terminal detent for the displacement movement of the valve piston, wherein the closure element is preferably a closure screw. Alternatively or additionally, the piston bore in the valve housing can have a step which represents a detent for the step of the valve piston.

According to a further optional modification of the invention it can be provided that the valve piston is equipped with a plurality of springs which permanently exert an effect of force on the valve piston or exert said effect of force only with in specific ranges in terms of the position of said valve piston. It is also possible herein that there are inter alia two springs herein which in the case of a form-fit thereof with the valve piston exert in each case forces in dissimilar axial directions.

The invention includes the presence of a plurality of control surfaces of the valve piston which can be impinged with identical or dissimilar pressure levels and which can be aligned in identical or opposite orientations.

Alternatively or additionally it can be provided that the valve piston is able to be impinged with a force which acts in the actual direction and is otherwise generated, for example by way of the servomotor, a proportional solenoid, etc.

It can moreover be provided that the driveshaft is a camshaft having single cams or multiple cams so as to be embodied as crankshaft or an eccentric shaft.

It can furthermore be provided that the piston is designed so as to be rotationally symmetrical in terms of the longitudinal axis of said piston. Said piston can have a first portion having a larger diameter which has a constriction, and a second portion having a smaller diameter which emanates from the first portion.

It can furthermore be provided that an inline piston pump according to the invention has a plurality of openings which are able to be utilized as high-pressure connectors. There is therefore the possibility of utilizing one of these openings as a high-pressure connector, whereas the other openings are to be closed in a high pressure-tight manner. Alternatively or additionally, it can be provided that an inline piston pump according to the invention has a plurality of openings which are able to be utilized as suction connectors. There is therefore the possibility of utilizing one of these openings as a suction connector, whereas the other openings are to be closed in a pressure-tight manner.

According to an optional modification of the invention it can be provided that the volumetric flows of a fluid to be pumped that are generated by a respective piston are not completely or not at all unified with one another downstream but are guided out of the pump by way of at least two separate high-pressure outputs.

In the presence of a plurality of high-pressure outputs, the latter in fluidic terms are typically connected to one another downstream of the displacement units. In terms of the consumers to be connected to the plurality of high-pressure outputs it can however be advantageous for the two consumers at the high-pressure side thereof being hydraulically separated from one another. There is also the possibility of supplying from a plurality of high-pressure connectors volumetric flows which as partial volumetric flows are already separated from one another to in each case separate hydraulic consumers and/or high-pressure inputs of a switch valve which at the output thereof can selectively discharge one of these partial volumetric flows or sums of volumetric flows which are based on said partial volumetric flows. The selection of the partial volumetric flows which are a component part of the sum of the volumetric flows is preferably able to be predefined by a remote action to the switch valve.

Therefore, at least one duct separator which in the high-pressure duct mutually separates the respective outputs in fluidic terms is provided in the inline piston pump according to the invention. The plurality of hydraulic consumers which are connected to the high-pressure outputs thus possess displacement units which are assigned exclusively to said hydraulic consumers, the volumetric output flow of said high-pressure outputs, or the hydraulic output performance thereof, respectively, not being able to be otherwise consumed. In the case of separate partial volumetric flows being supplied to a switch valve, the volumetric flows at the plurality of high-pressure inputs of the latter are in each case generated by exclusively assigned displacement units.

According to an advantageous modification of the invention it can furthermore be provided that the volumetric flow of a fluid to be pumped that is generated by a respective displacement unit is implemented downstream by selectively providing at least one duct separator which is inserted into the high-pressure duct.

Duct separators of this type, if required, can also be inserted only when assembling the inline piston pump such that the flexibility in terms of use of said duct separators is high.

It can be provided according to the invention that the at least two pistons have dissimilar diameters. The requirements of dissimilar consumers which are connected to dissimilar high-pressure output of the pump can be taken into account by providing a plurality of dissimilar diameters. The bore is which accommodate said pistons herein can be adapted to the respective piston diameters, or such bores which have a larger diameter can in each case be provided with a liner which matches the piston diameter.

Alternatively or additionally to the use of such duct separators, an inline piston pump according to the invention in the basic embodiment thereof can already have flow paths to the respective high-pressure outputs which in terms of the flow direction of the fluid to be pumped are separated, that is to say hermetically sealed from one another, downstream of the entry into the displacement units.

On account of the combination of a separation of ducts at the high-pressure side of an in light piston pump with a separate supply of said partial volumetric flows to such a switch valve which is conceived for providing a volumetric output flow, on the one hand, said volumetric output flow being variable such that said volumetric output flow is composed of the possibility of forming different sums which can be accumulated from said partial volumetric flows, there is the possibility of a variable volumetric output flow, even at a constant rotating speed of the driveshaft and at a constant setting of the installation by way of which the volumetric flow of the fluid to be pumped that able to be supplied to the at least one displacement unit is set. The variability herein is indeed restricted to the possibility of selecting between specific discrete values, this not enabling any continuous setting of a volumetric flow, but is however associated with comparable low complexity. Such a setting of the volumetric flow is ultimately possible even when the inline piston pump is operated at a constant rotating speed, or can only be operated at a constant rotating speed, respectively, and an activation of said installation by way of which the volumetric flow of the fluid to be pumped is set at the suction side is not required, or the presence of such an installation is not even required, respectively.

It can furthermore be provided that the driveshaft is driven by way of a primary drive, preferably an internal combustion engine or an electric machine which is preferably linked to the driveshaft by way of a gearbox.

According to a further optional modification it can be provided that a switch valve which selectively unifies the at least two separate high-pressure outputs from the inline piston pump and discharges the volumetric flow generated on account of the unification to a collective output or to a volumetric flow or selectively one of the two volumetric flows supplied at the input side. A highly variable volumetric flow can thus be generated, the variability of the latter being even increased in that the volumetric flows of the at least two dissimilar high-pressure output of the pump differ by virtue of dissimilar piston diameters of the associated displacement unit. It is evident to the person skilled in the art that the present invention is not limited to 2 high-pressure outputs and corresponding inputs at the switch valve.

The invention furthermore relates to a method for open-loop and closed-loop controlling of an inline piston pump according to the invention, in particular of the volumetric output flow, the performance, and the torque. It can be provided herein that the volumetric output flow is variable as a function of a rotating speed of the driveshaft and/or a degree of opening of an installation by way of which the quantity of the inflowing fluid to be pumped is variable at the suction side and or a switch valve which enables a variable sum to be formed by partial volumetric flows which can be generated in mutually separated units of an inline piston pump according to the invention.

In a modification of the method according to the invention for open-loop and closed-loop controlling of an inline piston pump according to the invention, in particular the volumetric output flow, the performance, and the torque, the control variable is variable as a function of a rotating speed of the driveshaft in the absence of a suction throttle valve or preferably at a completely open suction throttle valve.

In a refinement, the method for open-loop and closed-loop controlling of the volumetric output flow, the performance, or the torque of the inline piston pump according to the invention utilizes an installation by way of which the volumetric flow of the fluid to be pumped that is able to be supplied is set at the suction side, said installation in turn being able to be set by way of an actuator which in turn receives an actuation signal from the control apparatus. The control apparatus in one preferred variant receives at least one further item of information pertaining to another unit, or an input signal from said unit, respectively, which supplies a mechanical output to the inline piston pump according to the invention and/or receives a hydraulic output from the inline piston pump. Alternatively or additionally to this preferred variant, at least one operating variable of the inline piston pump according to the invention is supplied to the control apparatus.

The invention furthermore relates to a method for open-loop and closed-loop controlling of an inline piston pump, in particular the volumetric output flow, the performance, and the torque, wherein the inline piston pump possesses at least two mutually separated high-pressure outputs and thus can discharge at least two mutually separated volumetric flows which can in each case be directed into separate high-pressure inputs of a switch valve. It is provided herein that the actuatable switch valve as a function thereof provides a volumetric output flow which is the size of one of the potential sums formed from the input volumetric flows and is variable in the context of said degrees of freedom.

In a refinement, the latter method for open-loop and closed-loop controlling of the volumetric output flow, the performance, or the torque of the inline piston pump according to the invention utilizes a switch valve which can be set by a remote action, preferably by way of an actuator integrated in the switch valve, said actuator in turn receiving an actuation signal from the control apparatus. In a preferred variant, the control apparatus receives at least one further item of information pertaining to another unit, or an input signal from said unit, respectively, which supplies a mechanical output to the inline piston pump according to the invention and/or receives a hydraulic output from the inline piston pump. Alternatively or additionally to this preferred variant, at least one operating variable of the inline piston pump is supplied to the control apparatus.

BRIEF DESCRIPTION OF THE FIGURES

Further features, details, and advantages will become evident by means of the following description of the figures in which:

FIG. 1: shows a schematic sectional illustration of the inline piston pump according to the invention, viewed transversely to the driveshaft axis;

FIG. 2: shows a schematic sectional illustration of the inline piston pump according to the invention, viewed along the driveshaft axis;

FIG. 3: shows a perspective view of the inline piston pump according to the invention;

FIG. 4: shows a schematic sectional illustration of the inline piston pump according to the invention, viewed through the cover housing, wherein the valve piston of the suction throttle valve disposed therein is exposed;

FIG. 5: shows a perspective view of a centering element of the inline piston pump;

FIG. 6 shows a schematic sectional illustration of the inline piston pump according to the invention, viewed through the cover housing, wherein the suction throttle valve disposed therein;

FIG. 7 shows an enlarged view of a first longitudinal portion of the valve piston from FIG. 6, having an annular space;

FIG. 8 shows a schematic illustration of an exemplary embodiment for open-loop or closed-loop controlling of the inline piston pump with an electric machine;

FIG. 9 shows a schematic illustration of an exemplary embodiment of the elements acting in the region of the suction throttle valve;

FIG. 10 shows a further schematic illustration of the elements acting in the region of the control elements; a

FIG. 11 shows a graph for explaining an exemplary application for closed-loop controlling of the inline piston pump;

FIG. 12 shows a schematic illustration of an inline piston pump according to the invention, having two outlet connectors which are fluidically separated from one another; and

FIG. 13 shows a schematic illustration of a device according to the invention in which a variable volumetric flow is generated by way of a switch valve.

DETAILED DESCRIPTION

FIG. 1 shows a sectional view of an exemplary embodiment of an inline piston pump 1 according to the invention.

A displacement unit can be seen, said displacement unit comprising a piston 3 which compresses the fluid to be pumped that is introduced into an oil compression chamber by way of a first check valve, the latter being referred to as the suction valve 11, and which by way of a second check valves, the latter being referred to as the high-pressure check valve 10, discharges said fluid. A plurality of displacement units herein are disposed behind one another in the direction of the driveshaft axis 4. Each piston 3 is operatively connected to the driveshaft 3 and herein is disposed in such a manner that the longitudinal axis of said piston 3 is aligned so as to be ideally radial in relation to the driveshaft axis 4. The inline piston pump 1 preferably comprises three housing part 6, 8, 13. The lower housing part 6 which hereunder will be referred to as the main housing part 6, accommodates that part of the driveshaft 2 that lies in the interior of the pump, the Pistons 3, and the high-pressure check valves 10 at the high-pressure side (outlet valves) of the respective displacement units. An oil compression chamber comprises the entire volume in a displacement unit that is filled with the fluid to be conveyed, with the caveat that the suction valve 11 as well as the high-pressure check valves 10 of said displacement unit are closed.

The upper housing part 8, which is also referred to as the cover housing part 8, contains the suction valves 11 (in that valves). The two housing parts 6, 8 are mutually adjacent my way of a planar contact region 9 which is preferably flat.

For example, the volumetric flow of the fluid conveyed by the inline piston pump 1 can be adapted to a specific rotating speed of the drive by the control element 12 in that the suction-side inflow of the fluid to the inline piston pump 1 is restricted. The inline piston pump 1 has an advantageous constructive design and is embodied so as to be optimized in terms of the installation space.

As can be further derived from FIG. 1, the piston 3 is received so as to be movable in a reciprocating manner in a piston chamber 5 which is in part disposed in the cover housing part 8 and in part in the main housing part 6. The Bis 3 in the exemplary embodiment has a pin 31 which is disposed so as to be centric and which protrudes into the cover housing part 8. The upward and downward movement of the piston 3 takes place by virtue of the rotation of the driveshaft 2 which is provided with cams and of the spring 32 which is supported on the piston 3.

It can furthermore to be seen is also the fitting flange part 13 by way of which the inline piston pump 1 can be fastened to an element (not shown).

The operating procedure of the inline piston pump 1 is as follows. A fluid to be pumped first flows into the oil compression chamber by way of the suction valve 11, since the piston 3 is on its way from the upper dead center to the lower dead center. The spring 32 which is supported on the piston 3 ensures a movement of the piston 3 toward the lower dead center such that an operative connection between the piston 3 and the driveshaft 2 is continually guaranteed. An enlargement of the oil compression chamber and thus a negative pressure arises on account of the movement of the piston such that the suction valve 11 is moved, counter to the pre-tensioning force of the spring 16, to the open position of said suction valve 11, this leading to the fluid to be pumped in Vedic in the oil compression chamber, or be suctioned into the latter, respectively. The high-pressure check valve 10 is in the locked position thereof during this procedure.

The pressure in the oil compression chamber increases In a movement of the piston 3 away from the lower dead center toward the upper dead center, the suction valve closes, and the highly pressurized fluid by way of the high-pressure check valve 10, which is thereafter opened, flows out toward the high-pressure side of the inline piston pump 1.

FIG. 2 illustrates a sectional view of the exemplary embodiment discussed in the longitudinal direction of the driveshaft 2, from which sectional view the arrangement of the displacement units can be derived. A plurality of pistons 3, the respective longitudinal axes thereof being aligned so as to be ideally radial in relation to the driveshaft longitudinal axis 4, are disposed behind one another in the longitudinal direction of the driveshaft 2 and interact in each case with the specifically shaped portion of the driveshaft 2 such that approximately continuous conveying of the fluid results.

It can be seen that the three displacement units shown, which in geometric terms are disposed behind one another, upstream are connected to a common suction duct 40 by way of which the fluid to be conveyed is conveyed into the associated oil compression chamber by way of a respective suction valve 11. Fluid does not make its way from the respective oil compression chamber into the suction duct 40 in a movement of the piston 3 from the lower dead center to the upper dead center because the suction valve tappet 111 is urged to the closing position thereof by way of the force acting from the spring 16.

The force-fit between the spring 16 and the suction valve tappet 111, and the force-fit between the spring 32 and the piston 3, is enabled in that the two springs 16, 32 are supported on a centering element 15 which is rigidly disposed in that recess by way of which the piston chamber 5 is formed. The support of the spring 16, 32 on the centering element 15 accordingly lays the foundation for the contact pressure of the piston 3 on the cam of the driveshaft 2 by way of the spring 32, and the contact pressure of the suction valve tappet 11 on the contact face thereof, leading to the suction valve 11 being able to be closed by way of the spring 16 in the absence of negative pressure in the oil compression chamber.

The centering element 15 herein can be completely plug-fitted in the cover housing part 8 and be fixed therein by way of the main housing part 6.

The presence of a fitting flange part 13 which is fastened to the main housing part 6 and which centers the driveshaft 2 has that opening by way of which the end portion of the driveshaft 2 that is situated outside the main housing part 6 is guided directly to the outside can further be seen in FIG. 2. In the exemplary embodiment shown, the driveshaft 2 can be extracted from the main housing part 6 and installed in the latter when the flange part 3 is removed. Any accessibility of the driveshaft 2 here is provided only by way of the fitting flange part 3.

The invention includes a refinement in which accessibility is also provided by way of the cover side of the cylindrically-shaped housing portion of the main housing part 6 that faces away from the flange fitting part 13 (not illustrated in the figures). This can be provided by a subsequent conversion or by a corresponding construction of the main housing part 6. A corresponding preparation can be achieved in that the main housing part 6 at said cover side can be closed and opened by way of a cover which is embodied as a separate component. To the extent that the opening diameter on the main housing part 6 that can be closed by said cover is correspondingly sized, the driveshaft 2 can also be installed in the main housing part 6 and extracted from the latter through said opening. The fitting flange part 13, at the front side of the inline piston pump 1 where the driveshaft toothing for driving the inline piston pump 1 is situated, can thereafter be connected in an integral manner to the main housing part 6. The main housing part 6 in such an embodiment which is closed by said cover herein can be embodied in such a manner that a second inline piston pump 1 which is disposed in the opposite direction can be screw-fitted back-to-back to the first inline piston pump, and a rotationally fixed coupling of the two driveshafts 2 is possible by way of a corresponding toothing, wherein the shaping of the main housing part 6 takes place in such a manner that the driveshaft toothing is also covered by the two main housing parts 6 which are fastened to one another. In the case of such an upgrade, the two driveshaft chambers of the two combined inline piston pumps form a common volume. The contact region of the two main housing part 6 is closed by way of a sealing system.

FIG. 3 shows a perspective view of the inline piston pump 1 by means of which the housing construction in three parts can be seen. The cover housing part 8 is placed onto the main housing part 6 which in turn is connected to the fitting flange part 13.

The high-pressure connector 20 of the inline piston pump 1 herein can be disposed on a side on the main housing part 6 that is opposite the fitting flange part 13.

According to an alternative configuration, the fitting flange part 13 in terms of the exemplary embodiment of FIG. 2 can however also be disposed on the same side as the high-pressure connector 20, wherein the drive-side driveshaft portion in this instance is preferably guided to the outside through an opening and censoring region which is formed so as to be integral to the main housing 6, and the fitting flange part 13 in a state fitted on the main housing part 6 covers the drive-side part of the driveshaft 2 and in a state removed from said main housing part 6 exposes said end portion of the driveshaft 2 so that it is possible to connect to the driveshaft of the other component to be fitted. The discussed component to be fitted here can be an inline piston pump of identical construction or hydraulic pump of the different type or an electric machine, etc.

FIG. 4 shows a plan view of a section plane 91 which is disposed in the cover housing part 8, said plan view showing the piston bore and the valve piston 124 of the suction throttle valve. The annular space by way of which the fluid breaches the suction duct 40 can be seen along the exposed flow path from the suction connector 18. Furthermore to be seen are the three supply borers by way of which the fluid from the suction duct 40 can reach the piston chamber 5 in the case of an opened suction valve 11. There is a fluidic connection between a supply bore and the suction duct 40, said fluidic connection continuing up to the suction connector 18 in the case of an opened suction throttle valve. The suction throttle valve herein, as a function of the position thereof, can influence the quantity of the fluid to be conveyed flowing into the suction line.

The suction connector 18 herein does not have to be disposed on a lateral wall of the cover housing part 8, as illustrated, but can also be situated on another side of the surface, for example on the upper side of said cover housing part 8. It is also possible for a plurality of openings to exist, one of said openings being utilized as a suction connector 18 and all other said openings being able to be closed. This opening, or these openings, respectively, is/are preferably situated on the lateral wall and/or the upper side of the housing part 8.

FIG. 5 shows a perspective view of the centering element 15 which comprises an inner annular element 153 and a complementary outer annular element 152, wherein the inner annular element 153 and the outer annular element 152 are disposed so as to be mutually coaxial. The two annular elements 152, 153 herein are connected to a connection web 158, wherein the inner annular element 153 in the interior thereof has an inwardly directed flange region 154, the spring 16 for the valve tappet sitting on said flange region 154. The centric recess 155 can be penetrated by a pin 31 of the piston 3 in the case of a corresponding stroke of the latter.

It is furthermore to be noted that the driveshaft 2 can alternatively be embodied as a crankshaft or an eccentric shaft, wherein the pistons 3 in this instance have an indirect operative connection to said driveshaft 2. To the extent of the driveshaft 2 being embodied as a camshaft, a direct operative connection is preferable for reasons of cost. A direct connection means that the end side of the piston 3 contacts directly the opposite cam of said piston 3. A track roller, less preferably a ball bearing, or optionally also a friction element, by way of which rolling or sliding, respectively, on the rotating cam takes place can be fastened to the piston 3. An indirect operate of connection is consequently present between the piston 3 and the driveshaft 2.

For the sake of improved legibility, the term oil is used with reference to the fluid in the compound terms in the following explanations, such as oil pressure, oil flow, oil quantity, oil storage tank, oil dead volume, oil compression, etc.

Each of the displacement units at the input side comprises an inlet valve which is preferably embodied as a check valve and is referred to as the suction valve 11, the piston 3, and a check valve as an outlet valve at the high-pressure side, said check 12 being referred to as the high-pressure check valves. The inline piston pump 1 illustrated in the figures possesses three displacement units and is equipped with a camshaft 2 which has double cams (cf. FIG. 1). The three displacement units convey fluid—this herein can be oil—to a common high-pressure connector 17 of the inline piston pump 1.

It is achieved by way of a spring 32 that the piston 3 is supported on the opposite cam even in the suctioning operation. Since the cams in the exemplary embodiment are double cams, two lifting/lowering procedures of the piston 3 take place in a full rotation of the driveshaft 2. When an observed piston 3 in the course of the rotation of the camshaft moves from the upper dead center (OT) in the direction of the lower dead center (UT), a negative pressure results on account of the volumetric enlargement of the oil compression chamber of the observed displacement unit. The suction valve 11 opens by virtue of the higher oil pressure at the suction side, on account of which an oil flow is set in motion, said oil flow departing from the oil storage tank and flowing in the direction of the oil compression chamber of the observed displacement unit. The volume of the oil compression chamber is reduced after the lower dead center (UT) has been passed, as a result of the piston 3 continuing to further plunge into the receptacle recess 7 of said piston 3. The increase in pressure of the oil quantity enclosed in the oil compression chamber which arises on account thereof leads to the suction valve 11 closing. After a further increase in pressure, the high-pressure check valve 10 of the observed displacement unit opens. The two check valves of a respective displacement unit furthermore have the effect that different displacement units do not disturb one another in order to avoid that the oil brought to a high pressure level by one displacement unit does not reach the suction side by way of a neighboring displacement unit.

The analogous operated correlations between the piston movement and the switched states of the two check valves of a displacement unit would also be derived by using an eccentric shaft or a crankshaft.

The components for the suction valve 11 and the piston 3 of a displacement unit that are incorporated in the housing preferably all have an imaginary common longitudinal axis 71 which is directed so as to be radial on the driveshaft axis 4 (cf. FIG. 2).

This herein are the following components: a piston 3, a spring 32, a suction-valve valve tappet 111, a spring 16, and the centering element 15. The longitudinal axis 71 is likewise the longitudinal axis of the recess that forms the piston chamber 5 and of the receptacle recess 7 of the piston which adjoins the latter. Said recesses extend across the housing part 6, 8 and accommodate the latter.

The suction valve tappet 111 in terms of the shape can be similar to a thimble. The piston 3 in the receptacle recess 7 can be guided along the shell face of said piston 3 and is preferably embodied as a hollow piston. In one particularly preferred embodiment, said piston 3 on the side that faces away from the driveshaft 2 has a centric pin 31, the longitudinal dimension thereof exceeding that of the piston wall. On account thereof, an annular space in which part of the spring 32 is situated is present in the interior of the piston 3. The lower end of the annular space terminates on the inner base of the piston 3 on which the one end of the spring 32 is supported. The region of the spring 32 that faces away therefrom protrudes beyond the open upper side of said annular space. The end of the spring 32 there is supported on the centering element 15. An embodiment of such a centering element 15 that can be seen in terms of the details thereof is to be seen in FIG. 5 and will be explained hereunder. When the spring 32 is compressed to the minimum length thereof, which is possible in the installed state of said spring 32, it can be that said spring 32 is almost completely situated in the annular space of the piston 3. The cross-sectional face of this annular space has to be dimensioned so as to be correspondingly wide so as not to disturb the movement of the spring 32, but otherwise should be as small as possible in order for the oil dead volume to be delimited as far much as possible.

The shank-shaped portion of the suction valve tappet 111 has an internal diameter which is adapted to the external diameter of the inner wall 153 of the centering element 15, on account of which guiding of the suction valve tappet 111 takes place. A shoulder or a contact face 158 on which the spring 16 can be supported exists on the internal side of the inner wall 153 of the centering element 15. The opposite end side of the spring 16 is supported on the base of the blind bore of the suction valve tappet 111. The spring rate of the spring 16 is substantially less than that of the spring 32. The spring 16 has to be compressed to a corresponding extent so as to release the flow cross section at the suction valve 11 already at the only minor negative pressure which arises in the volumetric enlargement of the displacement chamber in relation to the pressure level prevailing in the oil storage tank. As has already been mentioned, the spring 32 by way of a correspondingly high restoring force has to ensure that the piston face of the piston 3 is pushed onto the cam contour also in the UT position.

In the operation of the inline piston pump 1, the movements of the piston 3 and of the suction valve tappet 111 take place in the direction of the imaginary longitudinal axis 71.

In a preferred embodiment the pin 31 of the piston 3 is embodied in such a manner that said pin 31 in the OT position fills an ideally large proportion of the remaining vacant blind bore volume of the suction valve tappet 111 (cf. FIG. 1). On account thereof, the partial volume in the blind bore of the suction valve tappet 111 which is alternatingly filled and not filled by the pin 31 contributes to the compression of the oil. Furthermore, a pin end that lies close to the base of the blind bore of the suction valve tappet 111 facilitates the rapid closing of the suction valve 11 when the piston 3, emanating from UT, moves in the direction of OT.

Three forces act on the tappet of the high-pressure check valve 10 (cf. FIG. 1). This tappet offers a contact face for the fluid situated in the high-pressure duct 17 of the inline piston pump 1. The restoring force of the spring of the high-pressure check valve 10 acts in the same direction, that is to say in the blocking direction of said high-pressure check valve 10. As soon as the oil pressure in the observed compression chamber is sufficiently high, the force acting in the flow direction of the high-pressure check valves 10 is sufficiently high in order for said high-pressure check valves tend to be opened. As long as the high-pressure check valve 10 is open, this displacement unit provides an hydraulic output which is discharged by way of the high-pressure duct 17 and the high-pressure connector 20 of the inline piston pump 1.

The guiding of the tappet on the high-pressure check valves 10 takes place in a manner analogous to that in the suction valve 11. As opposed to the suction valves 11 that are installed in the housing 8, an additional component according to FIG. 1 has in each case to be installed in the housing 6 for the high-pressure check valves 10 of the exemplary embodiment in order for the high-pressure check valves 10 to be high pressure-tight in the blocking direction.

A section plane by way of which a central longitudinal section through the piston 3 and at the same time a central longitudinal section through the suction valve 11 and likewise a central longitudinal section through the high-pressure check valves 10 is exposed exists for each of the displacement units. This section plane and the axis of the driveshaft 2 are preferably mutually perpendicular.

The central axis of the receptacle recess 7 for the piston 3 and that of the bore for the high-pressure check valves 10 in each of the displacement units are at a mutual angle in a range between 15° and 60°. An angular range between 25° and 45° is preferable.

Acute angles enable a minor dimension in terms of the width of the inline piston pump 1 and to a certain extent an increase in terms of the output density of the inline piston pump 1 and—this being potentially decisive in terms of the capability of the inline piston pump 1 to be installed on a specific drive assembly, for example on a power take-off of an internal combustion engine or on a multiple-circuit apparatus—however require a more intense deflection of the oil outflow of the fluid brought to the high pressure level. Therefore, particularly acute angles are unfavorable since the intense deflection leads to high pressure losses. Very particularly acute angles are also unfavorable because the installation height of the inline piston pump 1 is increased.

The centering elements present in the valves 10, 11 substantially contribute to the construction of the inline piston pump 1 illustrated as an exemplar example being able to be kept simple.

The exemplary embodiment of a centering element 15 which is perspectively depicted in FIG. 5 is also of a comparatively simple construction. The base has the shape of a circular disk which has two kidney-shaped openings and a circular opening 115 which is placed so as to be centric. The centering element 15 furthermore has two wall regions 153, 152 in the form of concentric circles. As can be seen, such a centering element 15 as a turned part can be machined largely from round stock while applying a single chucking procedure. Only the incorporation of the kidney-shaped openings has to take place elsewhere, for example by milling.

Two centering elements 15 per displacement unit (one per valve 10, 11) are used in the exemplary embodiment. In terms of the generic construction mode thereof, the centering element 15 used in the region of the suction valve 11 can be embodied exactly like the centering element 15 used in the high-pressure check valve 10. However, a centering element 15 of small dimensions is preferably used in the region of the suction valve 11 because of the limitation of the installation space targeted in the region of the high-pressure check valves 10, since comparatively small flow cross sections in the suction region, that is to say in the low-pressure region, are considered to be far more unfavorable than in the high pressure region.

The two kidney-shaped regions 15 in the perspective view of a centering element 15 illustrated in FIG. 5 are in each case a component part of the flow cross section and represent a local constriction along the flow path. As can be readily seen, a reduction in the external diameter of the centering element 15, while retaining all other dimensions which are independent of said diameter, leads to a decrease in the two kidney-shaped flow cross sections.

The housing of an inline piston pump 1 according to the invention is preferably composed of a main housing part 6 and a cover housing part 8 and a third fitting flange part 13 (cf. FIG. 2).

The main housing part 6 can have approximately the shape of two combine geometric base bodies, specifically the shape of the cylinder and the shape of the cuboid. The driveshaft 2 and the mounting thereof-exactly one mounting in the exemplary embodiment—in this design embodiment are situated in the interior of the cylindrical sub-region, whereas the internal volume of the cuboid sub-region accommodates the pistons 3 and the high-pressure check valves 10 and the high-pressure connector 20 of the inline piston pump 1.

The cover housing part 8 can have approximately the shape of a cuboid. The suction connector 18 is situated therein, and the suction valves 11 are situated in the internal volume of the cover housing part 8. Furthermore, that part of the installation 12 which serves for closed-loop or open-loop controlling of the inline piston pump 1 can be accommodated in the cover housing part 8. Such an installation 12 is preferably a suction throttle valve. The exemplary embodiment shown in FIG. 4 shows only a preferred embodiment of the valve piston 124 which is used for the suction throttle and incorporated in the bore thereof. Suction throttle valves are generally known to the person skilled in the art.

The housing part 6 and 8 are in direct mutual contact by way of planar contact of a contact region 9, or contact one another indirectly by way of sealing elements 19. This is particularly preferably a planar contact which lies on a plane E1 which runs parallel to the driveshaft axis 4. Very particularly preferably, in the context of the mathematical description of vector along the longitudinal axis 71 of a, or of each, respectively, receptacle recess 7 for a piston 3 is a normal vector to the plane E1.

In a first variant of the pump housing, the cylindrical sub-portion of the main housing part 6 does not have any covering face on that side on which the driveshaft 2 is guided to the outside.

The closing of the pump housing there is the responsibility of the component which is referred to as the fitting flange part 13 and which, as is highlighted by the name thereof, is embodied so as to be flange-shaped and to which the main housing part 6 is fitted, said fitting flange part 13 herein preferably bearing in a planar manner on the end side of the cylinder wall of the main housing part 6.

The driveshaft 2 on the side where said driveshaft 2 exits from the main housing part 3 is centered by the fitting flange part 13 and is guided to the outside by way of the longitudinal opening situated in said fitting flange part 13, and said driveshaft 2 in this longitudinal region is mounted by way of a front driveshaft bearing 48 which is inserted into the fitting flange part 13 (cf. FIG. 2).

The closed cover side of the cylindrical sub-region in the main housing part 6 is shaped in such a manner that the installed driveshaft 2 is preferably received by a rear driveshaft bearing 14 which is fastened directly to said driveshaft 2. No further driveshaft bearings are provided at least in the case of such inline piston pumps 1 having a comparatively small number of pistons. Roller bearings friction bearings can be used as driveshaft bearings. Friction bearings which can absorb radial forces and axial forces and are referred to as collar bearings are preferred.

The mounting of the driveshaft 2 having an axial fixing by a front driveshaft bearing 48 which is preferably fastened to the fitting flange part 13, and by a rear driveshaft bearing 49 which is preferably fastened to the main housing part 6, can be achieved in a simple manner by a corresponding tapering of the diameters at the longitudinal ends of the driveshaft 2.

The sealing between the fitting flange part 13 and the main housing part 6 takes place by way of a seal B, for example an O-ring. The sealing between the fitting flange part 13 and the driveshaft 2 takes place by way of a seal A, for example by way of an annular seal having a seal lip (cf. FIG. 2).

The main housing part 6 at the open end side of the cylindrical sub-region thereof has a plurality of projecting perforated lugs which terminate on a plane so as to be flush with the cylinder wall, said plane being provided as a contact face of the fitting flange part 13.

The cuboid region of the housing part 6 is preferably embodied in such a manner that said cuboid region encloses an ideally minor circumference of the cylindrical region. The hole pattern of said lugs in the form of prepared perforations can be incorporated therein already in the manufacturing of the fitting flange part 13, in particular when the fitting flange part 13 is made as a casting.

In an advantageous embodiment said hole pattern can be applied multiple times to the circumference of the fitting flange part 13. In this way, an inline piston pump 1 which without any major additional complexity can also be assembled in an installed position other than that originally/mainly envisaged. The inline piston pump 1 is able to be adapted in each case two different installation situations while adapting a single component, specifically while modifying the fitting flange part 13 or by selecting another type of flange, whereas all of the other components of the inline piston pump 1 can be retained without change. (For example, a flange of the SAE-B type could be used instead of the exemplary embodiment shown in the figures, in which a flange of the SAE-A type is present).

In terms of the main housing part 6 it can be advantageous when the cylindrical housing region thereof in the end region of the close longitudinal end thereof in geometrical terms is extended further than required by the mounting of the driveshaft 2. If such an additional installation is available, the corresponding cover face at the longitudinal end of the housing part 6 can be removed, and a further inline piston pump can be fitted, that is to say that a tandem arrangement of two inline piston pumps can be implemented. The modification on the main housing part 6 relates to the fitting of a further inline piston pump 1. The coupling of the driveshafts of the two hydraulic pumps can take place by way of a driveshaft toothing, for example. Instead of an inline piston pump 1 of identical construction, a rotational entrainment of a hydraulic pump of an entirely different construction, of an air compressor, or of an electric machine, etc. can of course also be implemented.

To the extent that the pump housing is constructed as described above, aluminum or an alloy which contains aluminum is preferably used for the fitting flange part 13.

In a further variant, which is not shown in any figure, the entire flange region of the inline piston pump 1 is situated directly on the main housing part 6, this indeed heavily restricting the flexibility in terms of being able to adapt to dissimilar installation space conditions, but by dispensing with the fitting flange part 13 as an additional separate component and without increasing the complexity in terms of the manufacturing of the main housing part 6 enabling a simple construction of a tandem arrangement of two inline piston pumps 1. In such an embodiment the fitting flange, which is situated on that side of the inline piston pump 1 where the driveshaft 2 is guided to the outside, is connected so as to be integral to the main housing part. The centering of the driveshaft 2, the receptacle of the front driveshaft bearing 48 and of the seal B, is thus situated in the main housing part 6. The seal B can be dispensed with. The installation and the extraction of the driveshaft 2 takes place by way of an opening of the driveshaft chamber which is situated so as to be opposite to the side of the main housing part 6 by way of which the driveshaft 6 is guided to the outside. This opening in the case of an installed driveshaft 2 is closed by a cover-shaped add-on part. The main housing part 6 is preferably designed in such a manner that said main housing part 6 can be screw-fitted back-to-back to another main housing part 6 which is disposed in the opposite direction. When a tandem arrangement of two inline piston pumps 1 is implemented in this way, the two driveshaft chambers form a common volume which preferably also covers the driveshaft toothing. The contact region of the two main housing parts 6 is closed by way of a sealing system.

It would have caused be conceivable that the inline piston pump 1 according to the invention in a third variant, for which there is likewise no figure, does not have a completely dedicated housing but part of the casing of said inline piston pump 1 is already a component part of another housing, that is to say that the inline piston pump 1 according to the invention would be used as integrated pump. Besides the modifications to be made directly on account thereof, the other features described here also are considered advantageous, particularly the retention of the features described in the following paragraph.

The joint between the main housing part 6 and the cover housing part 8 is preferably established in such a manner that the suction valves 11 are ideally situated completely in the cover housing part 8, whereas the receptacle recesses 7 of the pistons 3 are situated in the main housing part 6, and the high-pressure check valves 10 are ideally situated completely in the main housing part 6 or are ideally situated completely in the cover housing part 8 (not illustrated in the figures. For reasons mentioned above, the pin 31 which is situated on the piston 3 protrudes into the cover housing part 8. An assembly of this type offers the advantage that the components, or functional groups, respectively, mentioned are readily accessible for assembly/disassembly and can be moved to the respective final installed positions in the housing part 6 and 8, or be retrieved comfortably therefrom, respectively, by way of good accessibility.

The joint between the main housing part 6 and the cover housing part 8 is particularly preferably established in such a manner that the suction valves 11 are situated completely in the cover housing part 8, whereas the receptacle recesses 7 of the pistons 3 are situated completely in the main housing part 6, and the high-pressure check valves 10 are either situated completely in the main housing part 6 or completely in the cover housing part 8 (not illustrated in the figures). To the extent that the bore walls of the receptacle recesses 7, that is to say the contact faces of the piston walls, are situated only in the main housing part 6, the final manufacturing of said contact faces is obviously restricted to this housing part. Said division of the housing part 6 and 8 moreover offers the advantage that the contact face for the upper side of the suction valve At 111 can be incorporated directly into the cover housing part 8, despite the requirements in terms of dimensional accuracy and the surface finish of said contact faces herein being high in order for the suction valves 11 to close in a high pressure-tight manner in the blocking direction. If a corresponding special boring tool is available, this contact face can be made in one operating step conjointly with the machining of the depression in which the centering element 15 is assembled.

When assembling, or when disassembling, respectively, an inline piston pump 1 according to the invention, the two housing parts 6 and 8 are positioned in such a manner that the face thereof which in terms of the assembled inline piston pump 1 is situated on the contact region 9 which is preferably embodied as the plane E1 is exposed, and the assembly or disassembly, respectively, of the suction valves 11, the pistons 3, and the high-pressure check valves 10 can be performed while approaching from this side. Thanks to such housing structure, a positive accessibility for assembly and corresponding consequential advantages are achieved.

Instead of sealing all of the joints between the housing part 6 and 8 by discreet sealing elements 19, such a sealing system which has a plurality of individual seals, or at least one individual seal and at least one further structural element by way of which additional functions which are associated with the sealing is preferably inserted in the planar contact region 9 between the housing parts 6 and 8. The structural elements can be supporting sealing elements and check elements for visually and/or haptic leak checking the installed position and/or the installed orientation. The individual seals and structural elements are preferably applied to a seal carrier which is installed in its entirety when assembling the inline piston pump 1. The sealing system can contain positioning elements which render a wrong installation impossible or at least permit the latter to be identified from the outside.

The inline piston pump 1 can have at least one bore which is able to be utilized as a suction connector 18 and which is preferably situated on the cover housing part 8. As is illustrated in FIG. 4, a suction connector 18 can be disposed in such a manner that the oil connection, through a bore emanating from a longitudinal lateral wall or from the wall situated diametrically opposite the main housing part 6, preferably meets the suction duct 40 perpendicularly. If an installation 12 which is preferably embodied as a suction throttle valve is situated in the cover housing part 8, the suction duct 40 and the openings of which one is able to be utilized for accommodating the suction connector 18, and the one for accommodating the installation 12, are preferably disposed in a mutual relative position in such a manner that the bore of the suction connector 18 that meets the suction duct 40 meets in an ideally perpendicular manner from the bore to the accommodation of the installation 12 (cf. FIG. 4). Additional openings which are able to be utilized as a suction connector 18 can be provided order to achieve increased flexibility for fitting or installing, respectively, the inline piston pump 1, on account of which a certain flexibility exists for the opening which is actually used as the suction connector 18. Such a possibility would be, for example, the disposal of the further opening, the axis of which being embodied so as to be parallel to the respective piston movement directions of the inline piston pump 1. One of these openings in this instance is obviously used as the suction connector 18, and the other openings have to be sealed.

The inline piston pump 1 has at least one bore which is able to be utilized as a high-pressure connector 20, wherein said bore is preferably situated on that housing part 6 or 8 that accommodates the high-pressure check valves. A placing of a high-pressure connector 20 which can be implemented with little complexity is the continuation of the high-pressure duct 17, which can be seen in FIG. 1, to the outside, as can be seen in FIG. 3. An alternative or additional opening suitable for the placing is a bore which emanates from the longitudinal lateral wall of the housing part 6 and which meets the high-pressure duct 17 and preferably meets the high-pressure duct 17 in an ideally perpendicular manner.

Openings which are not required for further suction connectors and high-pressure connectors 20, 18 can be, or must be, respectively, closed in a pressure-tight manner. The possibility of being able to select one of various openings as the suction connector 18 facilitates the adaptation of the inline piston pump 1 to dissimilar conditions in terms of accessibility and installation space. The possibility of selecting one of various openings to be utilized as the high-pressure connector 20 likewise facilitates the adaption of the inline piston pump 1 to dissimilar conditions in terms of accessibility and installation space.

In order for the oil leakage from the driveshaft chamber, that is to say the cylindrical region of the main housing part 6 in which the driveshaft 2 is situated, to be discharged an oil connection can extend from there to the suction side, that is to say into the internal volume of the housing cover 8, wherein this oil connection preferably runs within the housing walls. This has the advantage that the leakage does not have to be first conveyed back to the oil storage tank but reaches directly the suction side of the inline piston pump 1. In terms of the flow direction of the fluid to be pumped, the line for discharging said oil leak which preferably terminates downstream of the installation 12. In order to avoid the driveshaft chamber being suctioned dry, and the corresponding consequential damage, the oil connection used as the leakage line can be equipped with a pressure relief valve.

In order for the leakage to be discharged from the housing part 13 there are preferably a plurality of oil connections which are disposed in such a manner that a discharge of the leakage is ensured independently of the fitting angle of the inline piston machine. For explanation: The main housing 6 at the preferred fitting angle is situated below the cover 8. By virtue of the conditions in terms of installation space it can however also be necessary for the cover 8 to be situated below the main housing.

FIG. 6 shows a schematic sectional illustration of the inline piston pump 1 according to the invention through the cover housing part in which the installation 12 which is disposed therein is embodied as a suction throttle valve for setting the volumetric flow of the fluid to be conveyed and is positioned by a closure element 21 and a spring 22.

It can be seen that the valve piston 124 in this exemplary embodiment is embodied as a differential piston which has a first longitudinal portion 121 having a comparatively large diameter, and the second longitudinal portion 122 having a comparatively small diameter. The second longitudinal portion 122 herein is guided in a correspondingly dimensioned bore, and the distal end of said second longitudinal portion 122 is situated in a control chamber to which an oil pressure can be supplied by way of the control pressure bore 23. The control pressure bore 23 can have a direct oil connection to the high-pressure side of the inline piston pump 1, or an oil connection which extends by way of a decompression unit 81, or have an oil connection to a pressure source which is hermetically sealed from the high-pressure side of the inline piston pump 1, that is to say with a pressure source which is hydraulically decoupled from the high-pressure side of the inline piston pump 1. As soon as the pressure level which is supplied by way of the control pressure bore 23 of the end side of the valve piston 121 that serves as the control surface reaches a specific threshold value, the further increase of said pressure level leads to an increasing displacement of the valve piston 124, counter to the force acting on account of the spring 22, in the direction of a constriction of the opening cross section formed by the suction throttle valve. The volumetric flow prevailing from the suction connector 18 to the suction duct 40 can be set by way of the position of the valve piston 124 and accordingly by way of the height of the control pressure supplied by way of the control pressure bore 23.

The valve piston 124 is preferably embodied as a differential piston and is particularly preferably embodied in two parts. The (thinner) second longitudinal portion 122 of the valve piston 124 is preferably designed as a needle roller, or while using a needle roller, respectively. The (thicker) first longitudinal portion 121 of the valve piston 124 has a taper 125 in a specific longitudinal region. In this way, there is an annular space in the piston bore of said valve piston 124 that is situated in the pump cover such that the size of the opening cross section present from the suction input 18 to the suction duct 40 is a function of the axial position of the valve portion 124. The valve piston 124 preferably has at least three contact faces and particularly preferably exactly 3 contact faces. In terms of the valve piston, the first contact face is formed by the shell face of the (thinner) second longitudinal portion 122 of the valve piston 124. The second and the third contact face are composed of the shell faces of two regions which are situated in the first longitudinal portion 121 of the valve piston 124 and are mutually separated by the taper 125.

FIG. 6 shows the valve piston 124 in the terminal detent position on the left side, or in that terminal detent position which is present when the control pressure is insufficient for overcoming the pre-tensioning force emanating from the spring 22, respectively. This terminal detent position of the valve piston 124 is achieved in that the shoulder region of said valve piston 124 bears on the base of the blind bore of the is cooled bore. Even while this is not exactly illustrated in FIG. 6, the maximum opening cross section in the suction throttle valve will be present in the terminal detent position of the valve piston 124, wherein a displacement of the valve piston 124 to the right, this being caused by a correspondingly high control pressure, leads to an increasing constriction of the opening cross section. In this terminal detent position, the annular space available on the valve piston 124 will thus interact, in particular be aligned, with the connection duct by way of which the fluid upon circulating around this annular space is guided to the suction duct 40 such that the throttling effect of the suction throttle valve actually reaches the minimal value thereof.

The valve piston 124 on the right side is pre-tensioned by a spring 22 such that the valve piston 124 bears on the left-side detent thereof. The region of the valve piston 124 having the significantly smaller diameter is preferably made from a needle roller 122 which is attached on that other component that forms the first longitudinal portion 121 of the valve piston 124 having the thicker diameter. The exposed piston face of the second longitudinal portion 122 can be utilized as a control surface of the valve piston 124 in that an oil connection is achieved by way of existing borers. An oil pressure prevalent there generates a force which, counter to the restoring force of the spring 23, causes a displacement of the valve piston 124. In order for a complete constriction of the suction input 18 to be prevented and for the self-lubrication of the inline piston pump 1 to be maintained, the closure element 21 which is illustrated in a heavily schematic manner and is preferably embodied as a closure screw has a pin which serves as the right-side terminal detent of the valve piston 124.

It has to be avoided in terms of leakage on the one hand, that a comparatively large oil quantity exits the control chamber, or the control pressure bore 23, respectively, and herein runs off along the gap between the second longitudinal portion 122 of the valve piston 124 and the piston bore, and herein reaches the base of the blind bore and increasingly accumulates there, which would lead to an excessively early terminal detent of the valve piston 124, this having the consequence that the suction throttle valve can no longer reach the position of the maximum opening of said suction throttle valve. In order for this to be avoided, a leakage discharge (cf. FIG. 7) can be provided. On the other hand, a certain supply of oil is required for lubricating the guide face of the piston 121.

FIG. 7 shows the proximal region of the first longitudinal portion 121 of the installed valve piston 124 from previously described FIG. 6.

The valve piston 124 there is configured according to a particularly advantageous embodiment of the invention. One can see the longitudinal bore 123 which is present along a line that is parallel to the longitudinal axis of said valve piston 123 and which penetrates the annular space formed by the taper 125. In order for said longitudinal bore 123 to be able to be reached by the oil leaking from the control chamber, a clearance 127 is situated on the end side of the (thicker) first longitudinal portion 121 of the valve piston 124 such that by including the volume achieved by the chamfer 126 of the piston bore there is an oil connection from the control chamber 23 to the suction side of the inline piston pump 1. It can be achieved by specially balancing of the flow resistance which results by way of said bore in the longitudinal direction of the valve piston 124—for example by way of a corresponding bore diameter or by inserting a correspondingly dimensioned throttle—that no accumulation of leakage oil arises on the end side of the (thicker) first longitudinal portion 121 of the valve piston 124 but there is nevertheless lubrication between the first longitudinal portion 121 of the valve piston 124 and the corresponding contact face of the piston bore.

FIG. 8 shows an exemplary embodiment of a device according to the invention in the first variant, specifically an inline piston pump 1 driven by means of an electric drive. This in the exemplary embodiment is an electric motor 50 which is operated by a three-phase current and which can be embodied as an asynchronous machine, for example. The supply of power can take place by way of the frequency inverter 70 which additionally functions as an actuator of the open-loop or closed-loop control, respectively. Adapting the electrical input power of the asynchronous machine 50 and the rotating speed thereof takes place by correspondingly setting the three electrical output voltages and the input frequency. A step-up gearing unit which is not illustrated in the drawing can be provided for adapting the rotating speed/torque between the asynchronous machine 50 and the inline piston pump 1. The operating range for the take-up speed and the torque supplied to the inline piston pump 1 can be covered by way of corresponding basic design. The inline piston pump 1 at the operating connector thereof, or the high pressure connected 20 thereof, respectively, can thus provide a controllable volumetric flow or a corresponding hydraulic output, respectively, which can be supplied to at least one hydraulic consumer and/or a pressure tank.

One electric drive unit is preferably also used in each case for each inline piston pump 1. However, a common use of parts or of the entire electric drive unit by a plurality of inline piston pumps 1 is also possible, in particular in the case of a tandem arrangement of pumps.

In the exemplary embodiment, the rotating speed of the asynchronous machine is fed back to the open-loop/closed-loop control unit which is associated with the frequency inverter 70 by way of a rotating speed sensor 51. There exist at least no direct feedback to the inline piston pump 1 for the actual value of the oil pressure at the operating output of said inline piston pump 1. The actual oil pressure value can optionally be detected by an additional sensor and likewise be supplied to the open-loop/closed-loop control unit associated with the frequency inverter 70.

In addition to the flows of information shown in FIG. 8, further flows of information may optionally be included: in particular a pressure signal which is fixedly correlated with the high pressure level of the inline piston pump 1, in particular the pressure level at the high-pressure duct 20 or at the high-pressure output 17 and which pressure signal is detected, for example, by placing an instrument such as a pressure sensor in the high-pressure duct 17 or at the high pressure connected 20, and/or a pressure signal which is fixedly correlated with the pressure level at the suction regions, in particular the pressure level at the suction connector 18 or in the suction duct 40. This enables closed-loop controlling and/or a cheque function of the inline piston pump 1.

FIG. 9 shows a further embodiment of the present invention. The spring 22 is mandatory in the schematic construction of the inline piston pump 1 which is driven by a primary drive 50 and is operated by way of an installation 12 embodied as a suction throttle valve, whereas the other two springs 222, 223 are optional so as to be able to achieve a more sophisticated characteristic line.

The valve piston in FIG. 9 is situated in the opened position and can be moved to the blocking position by being displaced to the left, in which blocking position only that volumetric flow which is required by the inline piston pump 1 for self-lubrication is still allowed to pass.

The spring 22 is preferably embodied as a compression spring—as is illustrated in the image shown. Alternatively, the restoring spring embodied as the spring 22 can be otherwise embodied, for example as a tension spring which is fastened to the valve piston 124 in such a manner that a restoring force emanating from said tension spring acts on the valve piston 124 independently of the position of the latter, wherein the restoring force emanating from the spring 22 is directed in such a manner that said restoring force acts counter to the force which engages in the presence of a pressure by way of the control pressure board 23 of the control surface of the valve piston 124. In this exemplary embodiment this control surface is impinged with the high pressure pHD of the inline piston pump 1. An internal supply of the high pressure is preferable in terms of construction in a solution. For example, the high pressure bore could be embodied as an oil connection between the high-pressure duct 17 and the control chamber.

If the spring 223 illustrated in FIG. 9 is absent, the schematic functions as follows. Below a specific first pressure threshold value, the force exerted on the control surface by the high pressure pHD is insufficient in order for said valve piston 124 to be moved away from the right-side terminal position (not illustrated) of the latter. At this terminal detent of the valve piston 124, the maximum possible opening cross section through the suction throttle valve, or from the suction input 18 to the suction duct 40, respectively, of the inline piston pump 1 is present. Upon exceeding this first pressure threshold value, the position of the valve piston 124 results from an equilibrium of forces of the restoring force of the spring 22 and the force which prevails by virtue of the pressure level pHD prevalent on the control surface. As the pressure level pHD increases, the opening cross section in the suction throttle valve is reduced until a second pressure threshold value is reached. The spring 222 thereafter reaches the detent face thereof such that the restoring forces of both springs act counter to the pressure level pHD prevalent on the control surface. Assuming that the pressure level pHD can reach correspondingly high values, a third pressure threshold value results. The valve piston 124 herein reaches the left-side terminal detent thereof (not illustrated). The suction throttle valve in this position of the valve piston 124 preferably has an opening cross section which is in terms of size is sufficient for supplying the inline piston pump 1 for self-lubrication, that is to say to avoid the latter running dry.

The presence of the second spring 222 in the form shown has the effect that the characteristic line of the suction input constriction is divided into two dissimilar regions. As mentioned, the presence of such a second spring 222 is optional. A third characteristic line range of the suction input constriction can obviously be achieved in that two springs 222′ and 222″ are used instead of a single spring 222. In such a construction, the impact of the spring 222′ on the detailed arises when the second pressure threshold value is reached, and the impact of the spring 222″ on the detailed arises when a third pressure threshold value is reached. The left-side terminal detent of the valve piston is reached only once a fourth pressure threshold value is reached.

Alternatively or additionally, a further characteristic line range of the of the suction input constriction can be achieved by the presence of a spring 223. A force-fit between the valve piston and the spring 223 is no longer present once the second pressure threshold value has been exceeded. Two springs 223′ and 223″ can be used instead of a single spring 223.

The presence of a spring 223 that an increased constriction of the pressure arises at comparatively low operating pressures pHD, whereas a less stringent constriction of the suction input arises on account of the presence of a spring 222.

A simple embodiment of a suction input constriction is likewise shown in FIG. 9, by way of which the oil pressure pHD at the high pressure connected 29, that is to say at the operating output, in the operating range of the inline piston pump is kept approximately constant to the extent that the spring in the operating range thereof has a constant spring hardness.

A force which in terms of the orientation of the block diagram is directed toward the right on the valve piston 124 of the suction throttle valve acts by way of the restoring force of an already pre-tensioned spring 222. A control surface present on the valve piston 124 is oriented such that an impingement or force thereon exerts a force on the valve piston 124 that is directed toward the right. The pressure level of the cut-off pressure of the inline piston pump 1 can be manually changed on account of an embodiment which enables a manual adjustment of the pre-tensioning of the spring. The pre-tensioning of the spring can preferably not be set to that range that permits that opening cross section at the suction throttle valve to be exceeded that is still just sufficient in order for the supply of the inline-piston pump 1 for self-lubrication to be covered, so as to avoid the latter running dry. In terms of construction, this can be achieved in that the closure element of the valve bore is provided with a correspondingly long pin which serves as the terminal detent of the valve piston 124

FIG. 10 shows a block diagram of the circuitry of the pump 1 and discloses further possibilities for utilizing the device according to the invention. Instead of the high pressure pHD being fed back directly to the valve piston 124, said control surface can be impinged by a so-called reduced pressure p_(red) which is derived from the high pressure pHD and which is obtained by way of the decompression unit 81. To the extent that the reduction is able to be variably set, for example while using an electrically actuatable pressure reduction unit, a variation of the cut-off pressure is also possible during the operation of the device according to the invention. Alternatively, the position of the valve piston 124 and thus the throttling of the oil supply at the suction side can be set by way of an externally generated pressure which can be built up by way of an auxiliary pump, for example, on account of which the volumetric flow of the fluid of the inline piston pump 1 can be set, as explained.

Alternatively (not illustrated) this control surface can have an all connection to the output of additionally present shuttle valve which by way of a first input (i) is connected to the high pressure pHD of the inline piston pump 1 or a pressure derived therefrom, and (ii) by way of a second input is connected to an externally generated pressure.

In a further alternative embodiment, the valve piston 124 can possess a second control surface which is likewise aligned in such a manner that a pressure level acting thereon likewise exerts a force on the valve piston 124 that is directed toward the left. In this embodiment the first control surface is impinged with the high pressure pHD of the inline piston pump 1 or a pressure derived therefrom, and the second control surface is impinged with an externally generated pressure.

In a further alternative embodiment, the valve piston can possess a second control surface which is aligned in such a manner that a pressure level impacting said control face exerts a force on the valve piston 124 that is directed toward the right. In this embodiment the first control surface is impinged with the high pressure pHD of the inline piston pump 1 or a pressure derived therefrom, and the second control face is impinged with an externally generated pressure. The spring 22 can also be dispensed with in such an embodiment.

The embodiments described enable the suction input connection to be variably changed and thus enable dissimilar characteristic lines which are also able to be influenced during the operation. On account thereof, a device according to the invention, assuming the availability of corresponding instantaneous variables, for example, can be used as an output-controlled inline piston pump pHD*Q=const, wherein Q is the volumetric flow of oil present at the operating output of the inline piston pump and pHD is the oil pressure there.

An externally generated control pressure can be, for example, the output pressure of an auxiliary pump or of an open-loop/closed-loop control valve or of the valve assembly which in hydraulic terms is preferably upstream of the installation 12 embodied as a suction throttle valve.

In terms of the drawing (FIG. 1) the pressure connector for feeding an externally generated control pressure to the valve piston 124 of the suction throttle valve is preferably installed on the upper side and/or the left external side of the cover housing part 8. All bores are in each case preferably present in the cover housing part 8 such that both options are available for said control pressure connector that is actually used as such. The opening for the pressure connector which is not required can in this instance be closed in a pressure-tight manner.

Alternatively or additionally to the possibilities mentioned to date for influencing the position of the valve piston 124, or for setting the opening width of the suction throttle valve in order for the suction input 18 to be influenced, mechanically or electro-mechanically operating actuators such as, for example, a proportional solenoid or an electric servomotor can be used.

The mention embodiments listed can be combined with one another. One example of an expedient combination is the use of a restoring spring and a proportional solenoid which exert a sum of forces on the valve piston 124 which act counter to that force at is applied to the valve piston 124 on account of the feedback of the high pressure pHD to the valve piston 124. Such combination enables the inline piston pump to be operated by the way of a variable characteristic line, reduces the required installation space of the proportional solenoid and the electric output required to supply the latter, and achieves the possibility of a precautionary measure that the inline piston pump 1 reverts to a safe operating state in the case of a malfunction of the proportional solenoid, for example on account of a broken cable.

FIG. 11 shows a further exemplary embodiment of the use of the inline piston pump 1 according to the invention. An oil pressure sensor 104 is situated at the operating output of the inline piston pump 1. However, a multiple sensor for detecting the oil pressure, the oil temperature, and the oil quality is preferably installed. The oil pressure sensor 104, or the multiple sensor, respectively, particularly preferably possesses an interface to a control apparatus 100.

The respective row signals of the sensor herein are converted to measurement signals by means of a converter 102, said measurement signals being supplied as a PWM signal, for example, or upon an analog/digital conversion, to the control apparatus 100 by way of a data bus. The control apparatus 100 receives further measured variables, for example the rotating speed of the primary drive 50, or variables from which said rotating speed can be calculated, respectively. The control apparatus 100 optionally receives further measurement and operating variables, specifically from other control apparatuses and/or from sensors, for example the emission of NOx from the exhaust gas treatment. The control apparatus 100 can furthermore have access to specific parameters, or parameters of this type, such as efficiency and emission maps of the internal combustion engine 50, for instance, are stored in said control apparatus 100, respectively. The direct or indirect actuation of at least one such actuator 101, for example servomotor, which can set the opening width of the suction throttle valve or, in general terms, carries out an actuation of the installation 12, can be performed by way of the control apparatus 100. The control apparatus 100 can optionally actuate further actuators. The control apparatus 100 can in particular be the control apparatus 100 of the primary drive 50, because a multiplicity of items of data which are relevant to the exemplary embodiment are in any way required on said primary drive 50.

Such a networking of the control functions of the internal combustion engine 50 and of the inline piston pump 1 achieves many advantages, independently of whether said functions are implemented in a common control apparatus 100 or in different control apparatuses which are however networked with one another in terms of information technology. The mechanical output to be supplied to the inline piston pump 1 in order for the latter to be able to provide the required hydraulic output, or the required volumetric flow, respectively, can be provided by the internal combustion engine 50 along the rotating speed/torque characteristic line of the best efficiency of said internal combustion engine 50, or along the rotating speed/torque characteristic line having the lowest emissions, or along an optimized rotating speed/torque characteristic line which takes into account the targets of high efficiency and low emissions in a specific mutual constellation, for example by strictly adhering to self-imposed emission limit values which at least conform to the exhaust-gas legislation or are more stringent and utilize the still existing margin for maximizing efficiency. The advantage of such a device lies in that said optimization can be dynamically adapted to the respective environmental conditions. A typical operating situation in which such a dynamic observation is highly advantageous arises when the internal combustion engine 50 is operated under the marginal condition in which the exhaust-gas treatment has not yet reached its operating temperature and therefore is not fully functional. It is advantageous for the device in such an operating situation to be operated in such a manner that the minimum raw emissions arise. Once the operating temperature of the exhaust-gas treatment has been reached, the rotating speed/torque characteristic line of the internal combustion engine can be repositioned such that improved efficiency is present.

Even more improved optimizations of this type are possible when the efficiency map of the inline piston pump 1 is likewise stored as a set of parameters in the control apparatus 100.

If variations arise in the hydraulic system which within a very short time require intense variations of the output values of the inline piston pump 1, that is to say the volumetric flow of the oil and/or the oil pressure, items of information of this type are immediately available to the control functions of the internal combustion engine 50. The corresponding actuator system of the internal combustion engine 50, for example the fuel injectors, can consequently already be actuated simultaneously with the valve piston 124 of the suction throttle valve of the inline piston pump 1. However, the delay in terms of the intervention of the control functions of the internal combustion engine 1 is avoided, said internal combustion engine 1 reacting only to a variation in the rotating speed that is unexpected from the point of view of said internal combustion engine 1, for example.

Instead (i) of a particularly rapid actuation of the suction throttle valve which, for instance, in the case of the demand for a significantly higher hydraulic output would lead to a comparatively intense collapse in the rotating speed of the internal combustion engine 50 and significantly extend the period until the rotating speed reaches approximately the nominal value thereof again (keyword turbo lag), or (ii) a comparatively slow actuation which does not exploit the dynamics of the internal combustion engine 50 and therefore would unnecessarily slow down the dynamics in terms of the application of the internal combustion/hydraulic drive system, the actuation of the suction throttle valve and of the actuator system of the internal combustion engine 50 can in each case take place so as to be mutually adapted in an optimal manner. For example, the actuation of the suction throttle valve in the case of a demand for a specific increase in the output at a still low oil temperature of the hydraulic oil can be carried out somewhat slower than would be the case if the hydraulic oil operating temperature had already been reached. The exhaust limit values which have to be adhered to can be limiting in terms of the dynamics of the internal combustion engine 50, in particular at low temperatures of the exhaust treatment system, said temperature is being present not only during and immediately after cold starting but even after comparatively long phases of idling.

FIG. 12 shows a schematic illustration of an inline piston pump according to the invention having to outlet ducts which in fluidic terms are mutually separated.

It is provided herein that the high-pressure duct 17 can be divided into at least two segments 17*, 17** which in turn can be hermetically sealed from one another. Each of these segments 17*, 17** can in each case supply the fluid which is highly pressurized by at least one displacement unit, wherein the segments are connected to dissimilar displacement units. The partial volumetric flows V1, V2, V3, V4 which emanate from the individual displacement units, or the displacement unit groups which are mutually separated at the high-pressure side, respectively, herein are not all fluidic the connected to one another downstream of the displacement units but are fluidic leads separated from one another by a duct separator 171.

At least one opening 120*branches off from each of those segments, said opening 120*being able to be used as a high-pressure connector.

It can moreover be provided that pistons 3, 3′, 3″ having dissimilar diameters are used such that dissimilar requirements of consumers to be connected can be taken into account.

FIG. 13 shows a schematic illustration in which a switch valve 72 which can connect to one another in various constellations the mutually separated high-pressure outputs 120*, 120**, 120** of the inline piston pump 1 is connected to the high-pressure outputs 120*, 120**, 120***of the inline pressure pump 1 having dissimilar piston diameters 3, 3′, 3″. The volumetric flow Q can thus represent an arbitrary combination of the individual volumetric output flows of the high-pressure outputs 120*, 120**, 120***such that a very high variability of the volumetric flow can be achieved.

To this end, the switch valve 72 can also be controlled by remote action 73. In essence, the three high-pressure inputs 92, 93, 94 of the valve 72 herein are fluidically connected to a respective one of the high-pressure outputs 120*, 120**, 120*** of the inline piston pump 1 and combined with one another in the interior of the switch valve 72, and directed to the high pressure collective output 95.

Further aspects of the present invention are to be found hereunder:

An inline piston pump (1), comprising:

a driveshaft (2) for driving the pump (1);

at least two pistons (3) which are operatively connected to the driveshaft (2) and are disposed along a driveshaft axis (4) and are in each case disposed so as to be movable in a reciprocating manner in a piston chamber (5);

a main housing part (6) for receiving the driveshaft (2) and for inserting the at least two pistons (3) in corresponding receptacle recesses (7); and

a cover housing part (8) for attaching to the main housing part (6),

wherein

the contact region (9) which is generated when attaching the cover housing part (8) to the main housing part (6) runs in a face, preferably in a plane, which exposes the piston chamber (5) of a respective one of the at least two pistons (3).

The pump (1) as claimed in aspect 1, wherein the contact region (9) is configured such that, in the case of the main housing part (6) and the cover housing part (8) being mutually separated, an insertion of the pistons (3) as well as of at least one pressure valve (10), preferably in the form of high-pressure check valves, into the main housing part (6) and an insertion of at least one suction valve (11) into the cover housing part (8) can take place.

The pump (1) as claimed in one of the preceding aspects, wherein the driveshaft (2) is embodied as a camshaft having single cams or multiple cams, as a crankshaft or an eccentric shaft.

The pump (1) as claimed in one of the preceding aspects, wherein the driveshaft axis (4) runs so as to be parallel to a plane formed by the contact region (9).

The pump (1) as claimed in one of the preceding aspects, furthermore having at least one suction valve (11) which is disposed in the cover housing part (8) and in an installed state preferably does not protrude beyond the contact region (9).

The pump (1) as claimed in aspect 5, wherein the suction valve (11) and the piston (3) of the respective displacement unit have an identical longitudinal axis.

The pump (1) as claimed in one of preceding aspects 5 and 6, wherein the respective longitudinal direction of the bores for receiving the at least one suction valve (11) runs so as to be perpendicular to a plane formed by the contact region (9).

The pump (1) as claimed in one of preceding aspects 5 to 7, wherein the cover housing part (8) comprises a plurality of suction valves (11) which are disposed in parallel beside one another.

The pump (1) as claimed in one of the preceding aspects, furthermore having at least one high-pressure check valve (10) which is disposed in the main housing part (6) and in an installed state preferably does not protrude beyond the contact region (9).

The pump (1) as claimed in aspect 9, wherein the longitudinal axis of the piston (3) and the longitudinal axis of a high-pressure check valves (10) of a respective displacement unit are situated on a plane which is preferably penetrated perpendicularly by the driveshaft axis (4).

The pump (1) as claimed in one of preceding aspects 9 or 10, wherein the main housing part (6) comprises a plurality of high-pressure check valves (10) which are disposed in parallel beside one another.

The pump (1) as claimed in one of the preceding aspects, wherein the respective longitudinal directions of the piston chambers (5) for receiving the pistons (3) run so as to be perpendicular to a plane formed by the contact region (9) and preferably emanate radially from the driveshaft axis (4).

The pump (1) as claimed in one of the preceding aspects, wherein the piston (3) has a pin (31) which in the installed state transgresses the plane formed by the contact region (9) and preferably protrudes into the recess (14) which accommodates the suction valve (11) of the same displacement unit, and preferably protrudes into the spring chamber of the compression spring (16) of the suction valve (11) that engages on a centering unit (15).

The pump (1) as claimed in one of the preceding aspects, furthermore having a device (12) which serves for closed-loop or open-loop controlling of the pump (1) and which is preferably disposed in the cover housing part (8).

The pump (1) as claimed in aspect 15, wherein this device (12) for closed-loop or open-loop controlling the pump (1) is a suction throttle valve (12) which is preferably disposed such that the longitudinal axis thereof is disposed so as to be parallel to the driveshaft axis (4).

The pump (1) as claimed in one of the preceding aspects, wherein the pump (1) comprises three mutually separable housing parts (6, 8, 13), preferably comprises only three mutually separable housing parts (6, 8, 13, specifically the main housing part (6), the cover housing part (8), and a fitting flange part (13).

The pump (1) as claimed in aspect 16, wherein

the main housing part (6) comprises at least one outlet (20) which is able to be utilized for a high-pressure connector, the high-pressure check valves (10) the driveshaft (2), at least one driveshaft bearing, and the recesses (7), the wall faces of said recesses (7) being the respective guides of the pistons (3), or the wall faces of said recesses (7) receiving the liners of the pistons (3), respectively;

the cover housing part (8) comprises at least one suction connector (18) and the suction valves (11); and

the fitting flange part (13) serves for guiding the driveshaft (2) out of an interior of the pump (1).

The pump (1) as claimed in aspect 16 or 17, wherein the driveshaft (2) is mounted by way of the fitting flange part (13) which is able to be incorporated in a sealing manner in a housing opening of the main housing part (6) such that the driveshaft (2) can be assembled from this side through the housing opening of the main housing part (6) that is provided for the fitting flange part (13).

The pump (1) as claimed in one of preceding aspects 16 to 18, wherein the main housing part (2) has at least two perforated fastening lugs which are aligned with one pair of a plurality of pairs of corresponding fastening bores in the fitting flange part (13) such that a plurality of fastening possibilities of the main housing part (6) rotated about the driveshaft (2) exist on the fitting flange part (13).

The pump (1) as claimed in one of preceding aspects 16, 18, and/or 19, wherein the main housing part (6), besides the opening that for guiding the driveshaft (2) out of an interior of the pump (1) is able to be reduced in size by the fitting flange part (13), has a further opening for guiding out the driveshaft (2), and the fitting flange part (13) is a cover part which is able to be fastened to the main housing part (6) in order for a driveshaft portion guided out of an interior of the pump (1) to be covered, wherein the main housing part (6) and the cover part in the case of the disassembled cover part are preferably designed such that the installation or the extraction, respectively, of the driveshaft (3) through the region of the main housing part (6) that is covered by the cover part is enabled.

The pump (1) as claimed in one of the preceding aspects, wherein the main housing part (6) is embodied in such a manner that the driveshaft (2) projects on two sides of the main housing part (6) such that a tandem operation of the pump (1) is possible without performing modifications on the main housing part (6).

The pump (1) as claimed in one of the preceding aspects, wherein a supply of the fluid to the suction valves (11) is guided by way of a common suction duct which runs so as to be parallel to the driveshaft axis (4).

The pump (1) as claimed in one of the preceding aspects, wherein a suction connector (18) is disposed in such a manner that said suction connector (18) is an extension of the common suction duct, or is disposed in a bore which meets this suction duct at a right angle.

The pump (1) as claimed in one of the preceding aspects, wherein the highly pressurized pumped fluid from the high-pressure check valves (10) is guided to the high-pressure connector by way of a common high-pressure duct which runs so as to be parallel to the driveshaft axis (4).

The pump (1) as claimed in one of the preceding aspects, wherein the central axis (71) of the recess (7) for the piston (3) and that of the recess for the high-pressure check valves (10) in each of the displacement units are at a mutual angle in a range between 15° and 60°, preferably in an angular range between 25° and 45°.

The pump (1) as claimed in one of the preceding aspects, wherein sealing elements (19) are placed in recesses of the main housing part (6) and/or recesses of the main housing part (8).

LIST OF REFERENCE SIGNS

-   1 Inline piston pump -   2 Driveshaft -   3 Piston -   3′ Piston -   3″ Piston -   4 Driveshaft axis -   5 Piston chamber -   5′ Piston chamber -   6 Main housing part -   7 Receptacle recess -   7′ Receptacle recess -   8 Cover housing part -   9 Contact region -   10 High-pressure check valve -   11 Suction valve -   12 Installation -   13 Fitting flange -   14 Recess -   15 Centering element -   16 Compression spring -   17 High-pressure duct -   17* High-pressure duct -   17** High-pressure duct -   18 Suction connector -   19 Sealing elements -   20 High-pressure connector -   21 Closure element -   22 Spring -   23 High pressure bore -   31 Pin -   40 Suction duct -   48 Front driveshaft bearing -   49 Rear driveshaft bearing -   51 Rotating speed sensor -   70 Frequency inverter -   71 Longitudinal axis -   72 Switch valve -   73 Remote action -   80 Hydraulic consumers -   81 Hydraulic unit -   91 Section plane -   92 High-pressure input -   93 High-pressure input -   94 High-pressure input -   95 High-pressure output -   100 Control apparatus -   101 Actuator -   102 Converter -   104 Oil pressure sensor -   111 Suction valve tappet -   120* High-pressure output -   120** High-pressure output -   120*** High-pressure output -   121 First portion of the piston having the large external diameter -   122 Second portion of the piston having the small external diameter -   123 Leakage bore -   124 Valve piston -   125 Taper -   126 Chamfer -   127 Clearance -   152 Outer annular element -   153 Inner annular element -   154 Flange region -   155 Centric recess -   158 Connection web -   171 Duct separator -   222 Spring -   223 Spring -   A Seal -   B Seal -   E1 Plane -   Q1 Volumetric flow -   Q2 Volumetric flow -   Q³ Volumetric flow -   Q Sum of different volumetric flows -   V1 Partial volumetric flow -   V2 Partial volumetric flow -   V3 Partial volumetric flow -   V4 Partial volumetric flow 

1. An inline piston pump, comprising: a driveshaft for driving the inline piston pump; at least two pistons which are operatively connected to the driveshaft and are disposed along a driveshaft axis and are in each case disposed so as to be movable in a reciprocating manner in a piston chamber; a suction connector for supplying a fluid to be pumped; wherein a suction valve is disposed in at least one, preferably in each, piston chamber in order to fluidically separate a suction duct for an inflow of fluid from the piston chamber during a compression movement of an associated piston; wherein an installation which is conceived for varying a volumetric flow of a fluid to be pumped between the suction chamber and the suction duct is provided between the suction connector and the suction duct which in fluidic terms is connected directly to at least one suction valve.
 2. The inline piston pump as claimed in claim 1, wherein a hydraulic installation is a valve which has a displaceable valve piston which is disposed in such a manner that a longitudinal axis thereof is preferably disposed so as to be parallel to the driveshaft axis, wherein the valve is preferably embodied as a suction throttle valve.
 3. The inline piston pump as claimed in claim 2, wherein the suction throttle valve has the displaceable valve piston for varying a degree of opening of a connection between the suction connector and the suction duct.
 4. The inline piston pump as claimed in preceding claim 3, wherein the displaceable valve piston has a flow region which, for varying a degree of opening of the connection between the suction connector and the suction duct, in a longitudinal direction of the piston is configured by a portion which is reduced in terms of a diameter thereof, wherein the flow region can preferably be designed as an annular space.
 5. The inline piston pump as claimed in claim 4, wherein the valve piston is a differential piston, thus possesses at least two regions which differ in terms of the diameters thereof, wherein the flow region is disposed in one of said regions, wherein the at least two regions which differ in terms of the diameters thereof are preferably configured in two parts.
 6. The inline piston pump as claimed in claim 5, wherein the region provided with the flow region has a leakage duct which runs in a displacement direction of the piston so that fluid emanating from a control bore or high-pressure bore, respectively, can be discharged to a suction side.
 7. The inline piston pump as claimed in claim 4, wherein the valve piston in the longitudinal direction thereof is supported on at least one restoring spring, and the valve piston has an operating face to which fluid can be supplied by way of a control bore or high-pressure bore, respectively, which is correspondingly placed in a corresponding housing part, wherein the operating face is directed in such a manner that a fluid pressure prevailing thereon exerts a force which is directed counter to a restoring force of the at least one restoring spring, wherein the operating face is preferably situated on the corresponding end side of the piston, and/or the valve piston when undershooting a pressure level in the control bore or high-pressure bore, respectively, below a specific threshold value is held in a first terminal detent position.
 8. The inline piston pump as claimed in claim 7, wherein the end of the restoring spring that faces away from the valve piston is supported on a closure element which is incorporated in a piston bore, and/or the closure element serves as a terminal detent for a displacement movement of the piston that is diametrically opposed to a first-mentioned terminal detent, wherein the closure element is preferably embodied as a closure screw.
 9. The inline piston pump as claimed in claim 7, wherein the suction throttle valve is equipped with at least one further compression spring which acts on the valve piston only once the restoring spring by virtue of a certain variation of the position of the piston is compressed by a certain length, and/or the suction throttle valve is equipped with at least one further compression spring which no longer acts on the valve piston only once the restoring spring by virtue of a certain variation of the position of the piston is compressed by a certain length.
 10. The inline piston pump as claimed in claim 7, wherein the piston is able to be impinged by a force which emanates from a servomotor, a proportional magnet and/or a supplied control pressure, for example, and is directed counter to the force that prevails on account of the pressure level supplied to the valve piston by way of the control bore or high-pressure bore, respectively.
 11. The inline piston pump as claimed in claim 6, wherein the control bore or high-pressure bore, respectively, is fluidically connected to a high-pressure output of the inline piston pump, wherein this preferably takes place by way of a hydraulic unit which from the high-pressure output of the inline piston pump can generate a reduced pressure level which is preferably able to be predefined by a remote action.
 12. The inline piston pump as claimed in claim 1, wherein the driveshaft is a camshaft having single cams or multiple cams so as to be embodied as a crankshaft or an eccentric shaft.
 13. The inline piston pump as claimed in claim 11, wherein the driveshaft is driven by way of a primary drive which is preferably embodied as an internal combustion engine and/or an electric machine, and/or a torque of the driveshaft that is provided by the primary drive is preferably supplied by way of a gearbox.
 14. The inline piston pump as claimed in claim 11, wherein a rotating speed signal which fixedly correlated with the rotating speed of the driveshaft is supplied back to an open-loop and/or closed-loop control installation, and/or a pressure signal which is fixedly correlated with a high-pressure level of the inline piston pump, in particular the pressure level at a high-pressure duct or at the high-pressure output, is supplied back to an open-loop or closed-loop control installation, and/or a pressure signal which is fixedly correlated with the pressure level at a suction region, in particular the pressure level at the suction connector or in the suction duct, is supplied back to an open-loop or closed-loop control installation.
 15. The inline piston pump as claimed in claim 14, wherein flows of a fluid to be pumped that are generated by a respective piston are not completely unified with one another downstream but are guided out of the inline piston pump by way of at least two separate high-pressure outputs.
 16. The inline piston pump as claimed in claim 1, wherein the at least two pistonshave dissimilar diameters.
 17. The inline piston pump as claimed in claim 15, wherein the flow of a fluid to be pumped that is generated by a respective piston is implemented downstream by selectively providing at least one duct separator which is inserted into the high-pressure duct.
 18. The inline piston pump as claimed in claim 15, wherein a switch valve which selectively unifies or does not unify the at least two separate high-pressure outputs from the inline piston pump and discharges the volumetric flow generated on account of a unification to a collective output is provided.
 19. A method for open-loop or closed-loop controlling at least one volumetric output flow of an inline piston pump as claimed in claim 1, wherein: the volumetric output flow is performed as a function of a rotating speed of the driveshaft in an absence of an installation, or at a constant setting of the installation at which an ideally low pressure loss exists along a suction path, that is to say from the suction connector to the suction duct.
 20. The method for open-loop or closed-loop controlling a volumetric output flow of an inline piston pump as claimed in claim 1, wherein: the volumetric output flow is variable as a function of a rotating speed of the driveshaft and/or of a degree of opening of the installation and/or by way of a switch valve.
 21. The method for open-loop or closed-loop controlling the output and/or the torque of an inline piston pump as claimed in claim 13, wherein the installation can be set by way of an actuator which receives an actuation signal from a control apparatus, and the control apparatus preferably receives at least one further input signal from another unit which supplies a mechanical output to the inline piston pump and/or receives a hydraulic output from the inline piston pump, and the control apparatus is supplied at least one operating variable of the inline piston pump. 